Even a low wattage is enough to kill a snake. That 113, and your snake has nowhere to go, will kill it. I've seen it happen to people in the hobby. If you had a 40 gallon tank and it blasted wide open, the snake could go to the other side to get away from the heat.
Also just because a snake can leave, doesn't mean it will. A snake can eat and not starve, but some will starve to death. Also have you seen how snakes have burn marks from heat rocks? They can not go on them, but they do. I'm speaking in actual facts, not just because the snake can.